The present application claims priority under 35 U.S.C. 119 of Japanese Patent Application No. 10-323887, filed on Nov. 13, 1998, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention relates in general to a facsimile machine that stores the image data of a scanned document in an image memory and then transmits that data to a remote party, and relates in particular to a facsimile machine that does not terminate storage of scanned document data even when, in the middle of scanning and storing image data in the image memory, the image memory becomes full, and further relates to a facsimile machine that is capable of reducing the amount of overall processing time needed from the start of scanning to the completion of data transmission.
2. Description of the Related Art
Today facsimile machines are often able to scan an entire document, encode the resulting image data, and temporarily store that data in an image memory before transmitting the image data to a remote machine (referred to as xe2x80x9cvia-memory transmissionxe2x80x9d or simply xe2x80x9cmemory transmissionxe2x80x9d hereinbelow) if they are used as a data transmitting device, and also able to save the image data for an entire document received from a remote party in the image memory before decoding the data and printing it out onto a recording sheet if used as a data receiving device. These facsimile machines can further be used as a photocopier which scans an entire document, encode the resulting image data, and temporarily store that data in an image memory before printing it out.
When such facsimile machines scan a document and store the image data of the document in an image memory, they generally scan the document xe2x80x9csequentiallyxe2x80x9d, one line at a time, convert the one line of scanned image to binary data, temporarily store the data in a buffer memory, encode the data and then store it in the image memory. They then repeat a series of these processes for the subsequent lines of the document page. Consequently, such a facsimile machine is unable to encode binary data for the next line of a document until the coding operation for the previous line of the document is completed. When the image being scanned in this manner is a data-intensive image such as a picture, scanning one page of a document may require a great deal of time.
In an attempt to solve this problem, facsimile machines have been provided with page buffersxe2x80x94either comprising part of the image memory or as an independent elementxe2x80x94for storing one document page worth of image data in binary form. The one page of image data stored in the page buffer is then sequentially coded and stored in the image memory, thus speeding up the per-page encoding and per-page scanning speeds.
Capacity of the image memory and memory space is limited, however, and particularly when such facsimile machines load into this limited memory the image data of another document to be transmitted or copied, or when data is received from a remote party and stored in the memory and the printing is being executed, the memory may then become full in the middle of the new scanning operation, thus resulting in the termination of scanning, the need to rescan the document, increased total transmission time, and increased frustration for the operator.
It is thus an object of the present invention to provide a facsimile machine which does not terminate the data storage operation even when the image memory becomes full during the loading of image data into the image memory, and which is also capable of reducing the amount of processing time, from the start of scanning to the completion of data transmission, needed to transmit a document.
In order to accomplish this object, in a facsimile machine according to a first aspect of the present invention, as soon as the amount of data stored in the image memory reaches a predetermined level during the encoding and storing of image data for a document being sequentially scanned, transmission of the encoded image data to a designated recipient from the image memory is immediately initiated. If the vacant space available in the image memory for storing the image data of a document being scanned becomes insufficient (i.e., the image memory becomes full), scanning of the document is suspended, transmission of all the encoded image data that is stored in the image memory is initiated, and after completion of this transmission, scanning and encoding of the document is resumed. In this case, the encoded data is transmitted directly to the recipient without being stored in the image memory.
Thus, when the predetermined data level is set at one document page of image data, for example, the remote facsimile machine is dialed immediately upon reaching the one page level of data in the image memory, and transmission of the coded image data stored in the image memory is initiated.
Furthermore, if, for example, space in the image memory is taken up by image data received from a remote source, and space in the image memory becomes insufficient for storing additional image data during scanning of a document for transmission, the scanning of the document is suspended, and all of the encoded image data for transmission that is stored in the image memory is immediately transmitted to the remote party, after completion of which sequential scanning is resumed; and the document is transmitted as it is encoded. Thus, the scanning operation is not terminated in the middle of scanning a document even when the image memory becomes full, unlike the case of prior art machines. Consequently, the document need only be loaded once into the machine (or reloading of the document is never required after completion of the scanning), thus reducing time and hassle, particularly when sending data-intensive documents.
When the facsimile machine receives from the recipient (e.g., a remote facsimile) data indicating the encoding capability of the recipient after it initiates transmission of the image data from the image memory to the remote facsimile, it preferably changes the encoding scheme for the data to be transmitted that is stored in the image memory to an encoding scheme of within the capabilities of the remote facsimile. The facsimile machine of the present invention may be capable of employing MH, MR, MMR, JBIG and other encoding schemes. When the facsimile machine dials a remote party and receives a transmission procedure signal from the remote party, which carries data indicating the encoding scheme of the remote party, the facsimile machine may select an encoding scheme to match the encoding scheme indicated by that data. Therefore, the encoding method for the image data stored in the image memory can be changed according to the encoding method of the remote party. In particular, the encoding method employed by the facsimile machine of the invention can be set to the most efficient common coding method with the highest compression rate shared by the two parties, thus enabling even faster transmission of facsimile data.
According to a second aspect of the facsimile machine of the present invention, image data from a document being scanned is temporarily stored in a page buffer, encoded, and then stored in an image memory. As soon as the amount of data stored in the image memory reaches a predetermined level, transmission of the encoded image data to a designated recipient from the image memory is immediately initiated. If the space available in the image memory for storing the encoded data becomes insufficient, scanning of the document is suspended, and all the encoded image data that has been stored in the image memory is transmitted to the recipient. After that, the image data stored in the page buffer data is encoded and transmitted to the recipient. Then, scanning of the document is resumed, and the resultant image data is encoded and transmitted directly to the recipient without first being stored in the page buffer or image memory.
Thus, when the predetermined data level is set at one document page of image data, for example, as soon as the one page of data for transmission has been loaded into the image memory, the remote party is dialed and the data in the image memory is transmitted. Furthermore, if, for example, space in the image memory is taken up by image data received from a remote source, and space in the image memory becomes insufficient for storing additional image data during scanning of a document for transmission, the facsimile machine suspends scanning of the document and immediately transmits all of the encoded image data for transmission that is stored in the image memory, and then encodes and transmits the image data stored in the page buffer. The facsimile machine then resumes scanning the document, encodes the image data and transmits the encoded data to the recipient.
Thus, in addition to the benefits of the first aspect, the image data stored in the page buffer in the form of binary data is not lost, and can be used in an effective manner to help expedite the data transmission.
It should be noted that the exact figures of one page for the predetermined memory level is used for exemplary purposes only, and could be set to an arbitrary proportion of total image memory, such as preferably 10%, 20%, etc.